Updated 31 July 2014

Experts warn against Noakes diet

Experts in the fields of dietetics and heart disease caution against changes to conventional diets and treatments despite radical new ideas about the link between high blood cholesterol and heart disease.

"There will be no change in how students at UCT are taught about the risk
factors for heart disease," Professor Bongani Mayosi, Head of the Department of
Medicine at the University of Cape Town has said.

“It is clear to me that the Diet-Heart hypothesis is alive and well and we do
not see any reason to change what we teach our students about the link between
an unhealthy diet, high blood cholesterol
and heart
disease,” he said.

Mayosi was reacting to a controversial UCT centenary debate between Professor
Tim Noakes and Dr Jacques Rossouw, a Washington-based epidemiologist and former
director of the Medical Research Council’s Institute for Nutritional Diseases,
last month, which saw the two medical heavyweights go head to head over the most
fundamental causes of heart disease.

Noakes, whose controversial
ideas on the diet-heart hypothesis have been widely publicised in the last
year, proposed during the debate, that high blood cholesterol is not a risk
factor for heart disease as it’s been billed for more than three decades, and
that conventional dietary recommendations do more harm than good. Rossouw
presented research to contradict this theory and warned of the dangers of the
medical profession turning its back on the more widely accepted causes of heart
disease.

"Noakes’s theory has the potential to divert people from diets and treatments
that are known to do good," said Rossouw.

Carb-resistance – fact or fallacy

Noakes believes that human health began deteriorating about 12 000 years ago
with the introduction of agriculture, but dipped severely in the last 35 years
following introduction of the 1977 United States Department of Agriculture
Dietary Guidelines, based on a 1953 idea proposed by Ancel Keys (PhD) that
dietary fat increases the blood cholesterol concentration which clogs major
arteries causing heart disease and stroke.

Contrary to this widely accepted finding, Noakes believes that not
everyone metabolises carbohydrates safely and a large population has genetic
carbohydrate resistance which becomes worse with age. Obesity, he proposes, is
the result of a carbohydrate-intolerant individual eating a high carbohydrate
diet.

Rossouw agrees that certain people are carbohydrate intolerant
before becoming diabetic, but believes obesity causes carbohydrate intolerance,
not the other way around. He argues that the proportion of truly
carbohydrate-intolerant people runs to about 6% while Noakes claims this figure
is at least 10 times higher.

Dr Rossouw was in Cape Town as a guest of the Chronic
Diseases Initiative in Africa (CDIA). A highly respected medical
professional, he has worked with the National Heart, Lung, and Blood Institute
(NHLBI) of the National Institutes of Health in the USA since 1989 and served on
the NHLBI National Cholesterol Education Program.

Good cholesterol, bad cholesterol

At the UCT debate Rossouw presented extensive data collected over many
decades that supports the current consensus that blood cholesterol occurs as
‘good’ HDL cholesterol, which protects arteries by removing cholesterol from
artery walls, and ‘bad’ LDL cholesterol that carries cholesterol molecules into
the artery walls.

“This is true for men and women, people of all ages and those with diabetes
and after suffering a heart attack. High levels of ‘bad’ cholesterol can be
treated with a group of drugs called Statins, which reduce heart attacks in
people using them,” he said.

“The science is clear that if one follows an unhealthy diet high in fat, one
increases one’s ‘bad’ cholesterol levels causing heart
attacks and angina,” said Rossouw. He also showed that people who had
inherited high ‘bad’ cholesterol levels had heart attacks at an early age while
those lucky people who were born with very low levels of ‘bad’ cholesterol lived
to a ripe old age without any heart disease.

All fats are not equal

The data presented by Rossouw supports current dietary guidelines and he
emphasised that since these were shown to improve health, they should not be
altered.

The dietary recommendation for a healthy heart is to eat
a varied diet while reducing fat intake, particularly saturated fats from
animal products and giving preference to fish, chicken, low-fat dairy products
and legumes. Eating unrefined carbohydrates, such as whole grain products and
focusing on more fruits and vegetables for sufficient vitamins and minerals,
such as potassium. Fibre is also recommended. Salt and alcohol intake should be
moderate.

Rossouw explained that the trend of increasing obesity
could be attributed to factors like poor diet, lack of physical activity and the
environment in which people live. “The association between overweight and
diabetes,” he said, “is clearly illustrated, as is the benefit of losing weight
to prevent diabetes. The data shows that reduced calorie diets result in
clinically meaningful weight loss, regardless of which foods are present in low
calorie diets.”

Rossouw agrees with Noakes that fast foods and sugar pose a danger to a
healthy heart, but differs on the value of unrefined carbohydrates. “Noakes's
definition of refined is anything above a glycaemic index of 40, which excludes
most carbohydrates except leafy vegetables. He asserts that they produce a large
glycaemic load which in time causes problems and wears out the pancreas,
producing diabetes and obesity. Therefore bread, pasta, rice and bananas should
be avoided.”

Diverting people from what’s good for them

Rossouw warns, “Noakes maintains that diabetics do not have higher blood
cholesterol levels than other people, that half of all heart attacks occur in
people with normal blood cholesterol, that glucose is the single most important
predictor of risk and a high-fat diet reverses almost all coronary risk factors.
Except for a very few close followers, the scientific evidence is clear and he’s
flying against it. There is now absolute proof that high blood cholesterol is
causal in heart disease.”

Debate convenor and Associate Director of the CDIA, Professor Krisela Steyn,
agrees. “Noakes’ diet is particularly dangerous for a certain part of the
population at high risk for kidney failure, with high cholesterol or ischaemic
heart disease. The general public will also be at increased risk if this diet is
followed for a long time. Damage is being done by radically oversimplifying
things and not basing public statements on the best available data.”

Dr Vash Mungal, CEO of the Heart and Stroke Foundation South Africa points
out, “Any diet that is calorie and energy restricted will reduce weight. But
caution should be used when generalising and saying that everyone should eat
fats, no sugar and no carbs, especially when there is no long-term data on this,
while there is extensive data on the conventional diet.”

According to Professor Steyn the Cochrane Collaboration at the Medical
Research Council will release a formal review of all existing data on the
subject in the near future.

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